THE only legacy of tragedy and terror is that hopefully we learn from heartbreaking experience.

I pray that law enforcement in West Virginia, probing a possible copycat sniper or snipers, have learned that.

Specifically, I am talking about lessons that should have been learned from last October’s civil terror in the “D.C. Sniper” attacks.

The heart of the investigation was grimly highlighted by the fact that law enforcement down there simply didn’t know what they were doing.

After 20 shootings and 13 deaths, there were no less than five different jurisdictions in three states investigating the horrors.

At the time, retired veteran cop Bo Dietl told me, “The investigators are all probably very good men and women, but it was amateur-hour time.”

Dietl, now chairman of one of the most active security and investigative companies in the country, was involved in some of the biggest murder probes in New York City history.

But here is the real lesson about that bungled and bloody probe. Police Chief Charles Moose, in Maryland, kept investigation developments so close to his chest that he had an entire tri-state area running after ghosts.

While he was roundly praised, people somehow forgot something. He refused to make public vital information that eventually led to the arrest of shooters John Allen Muhammad and Lee Malvo.

But for 21 days, he sat on information that, if made public, would have had an entire population helping out in the investigation.

Tips that two men in a dark blue Caprice with New Jersey plates were seen at some of the shooting scenes were ignored and not publicized.

When, on Oct. 23, soon after midnight, Chief Moose revealed they were no longer looking for a white van, but a dark colored Caprice, the public was on the lookout. Two- and-a-half hours later, a trucker who had heard about the description saw that Caprice, saw the license plate, drove his truck to block off an escape, at a rest stop in Maryland, and called the cops.

Simply put, after 22 days of block-and-stall press conferences, after the description was made public, the bad guys were caught within two-and-a-half hours.

The press, no matter what you think of us, can be a handy tool, and I know that cops in this case think that way, too.